1. Technical Field
The present invention relates to a printing apparatus or the like which can contain at least one printing material container attached thereto.
2. Related Art
Some known printing apparatuses, which contain at least one printing material container (ink container or the like) attached thereto, have a detection circuit configured to detect attributes and states of the at least one printing material container, such as a kind thereof and the presence or absence of the attachment thereof, and another circuit (a printing-material amount detection circuit) configured to detect whether the amount of a printing material contained in the at least one printing material container is more than or equal to a predetermined amount, or not. With respect to such a printing apparatus which is configured in such a manner as described above, known examples of a technology which enables prevention or suppression of occurrence of failures in the at least one printing material container and the printing apparatus due to any short circuit between the detection circuit and the printing-material amount detection circuit, include a technology described in Japanese Patent No. 4539654.
Further, known examples of a short-circuit protection circuit for a charging-type secondary battery pack having a remaining-amount indication function include a short-circuit protection circuit described in JP-A-5-299123.
This short-circuit protection circuit described in JP-A-5-299123 employs a method in which the presence or absence of an output electric current which arises upon occurrence of any short circuit is determined by measuring voltage-level changes of an electric-current detection resistor provided at the output portion of the secondary battery pack. But, it is to be noted that, in order to suppress loss of energy, the electric-current detection resistor needs to be of relatively low resistance. In this regard, however, the relatively low resistance of the electric-current detection resistor lowers a detected voltage level resulting from a current-to-voltage conversion, and thus, a determination circuit for determining whether any short circuit exists, or not, needs to be of higher accuracy.
In order to realize such a determination circuit of higher accuracy, a method of realizing the determination circuit by means of an analog circuit, which is configured to operate between a first power supply voltage (having a voltage level of, for example, 0V) and a second power supply voltage (having a voltage level of around several volts, that is, for example, approximately 3V to 5V), is employed. In such a circuit configuration, a short circuit is detected by measuring voltages of both terminals (two terminals) of the electric-current detection resistor. But, the voltage levels of the respective two terminals fluctuate, and thus, obviously, the fluctuations thereof cause a further variation in accuracy of the measurement.
Moreover, in the case where a high voltage (having a voltage level of, for example, approximately several ten volts) needs to be handled, a level conversion circuit is additionally needed, and thus, obviously, the addition of the level conversion circuit makes the circuit configuration further complicated.
Furthermore, since a protection circuit operates after the occurrence of a short circuit has been determined, a short-circuit electric current due to the short circuit is likely to flow even during a short period of time.